Teaching objectives

1. Make students understand the quantitative relationship of practical problems such as "How many" in specific situations and calculate them correctly.

2. Enable students to find and put forward the actual problem of "how much is it" in life and solve it effectively, and cultivate students' awareness and ability of mathematical communication.

3. Let students develop the habit of marking units when solving practical problems in writing; Let every student get a successful experience and enhance their interest and self-confidence in mathematics learning.

Key points: Understand the quantitative relationship of practical problems such as "How much was there" and calculate it correctly.

Difficulties: understand the meaning of the question, find the quantitative relationship and determine the method of solving the problem.

Teaching process:

View import

Calculate the addition of carry within 20.

Review the addition of 9 plus several, 8, 7, 6 plus several, 5, 4, 3, 2 plus several.

Teacher: Today we are going to use these additions to solve practical problems in life.

(blackboard title: solve the practical problem of "how much". )

Explore new knowledge

The courseware shows Example 6 on page 98 of the textbook.

Teacher (showing the information in the example): What information do you know from the picture?

Teacher: Explain what is "original"?

(Two people at the same table talk to each other. )

Observe the courseware drawing and find out the problems with known conditions and requirements. (Discuss in groups, report and communicate. )

Teacher: The total is divided into several parts. What are they, how many are there, and how to solve them?

The total is divided into two parts, one part is taken away and the other part is left behind. "Finding the original number" is solved by addition. )

Teacher: According to the known conditions and questions, can you make up an application problem by yourself?

The PE teacher took away seven whistles, and there were five left. How many whistles are there? )

Teacher: What does 7 mean? What does 5 mean? What does 12 mean? How did you solve the problem in a column?

[7 means take away, 5 means stay, 12 means original. The formula is 7+5 = 12 (unit)]

Integrate applications

Do it on page 98 of the textbook.

Teaching reflection

Through the study of this lesson, we know that the actual problem of "how much is a * * *" and the actual problem of "how much was it" are calculated by addition.

In teaching, students should read the questions carefully in the situation, understand the quantitative relationship of practical problems such as "how many", find out the problems with known conditions and requirements, and calculate them correctly.